I. Field of the Invention
The present invention relates to a differential pressure monitor.
II. Description of the Prior Art
There are a number of previously known monitors for measuring a differential pressure between two fluid ports. Many of these previously known devices use diaphragms for small differential pressure values and relatively small pistons for higher pressure values, i.e. differential pressures in excess of 10 psi. Low pressure differentials require correspondingly large areas to insure reliability of monitor performance, but the diaphragm constructions available are not compatible with many of the fluids used.
A still further disadvantage of these previously known fluid pressure monitors is that such monitors become damaged if system pressures exceed a relatively low amount. Monitors with adequate differential areas for use with higher pressures and/or corrosive or otherwise difficult fluids have not been available.
A still further disadvantage of these previously known differential fluid pressure monitors is that it is difficult, if not altogether impracticable to clean the moving parts in cases where fluids carry solids or other ingredients which tend to clog and prevent reliable operation.
A still further disadvantage of the previously known monitors is that such prior devices do not include any convenient means for bleeding air from the monitor. Air within the monitor, however, results in inaccurate readings, and with many fluids cause drying, hardening, and subsequent interference with monitor performance.